package com.bsh.erp.tools;

import java.util.Random;

public class RandomUtils {   
        public static final String allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";   
        public static final String letterChar = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";   
        public static final String numberChar = "0123456789";   
  
        /**  
         * 返回一个定长的随机字符串(只包含大小写字母、数字)  
         *  
         * @param length 随机字符串长度  
         * @return 随机字符串  
         */   
        public static String generateString(int length) {   
                StringBuffer sb = new StringBuffer();   
                Random random = new Random();   
                for (int i = 0; i < length; i++) {   
                        sb.append(allChar.charAt(random.nextInt(allChar.length())));   
                }   
                return sb.toString();   
        }   
  
        /**  
         * 返回一个定长的随机纯字母字符串(只包含大小写字母)  
         *  
         * @param length 随机字符串长度  
         * @return 随机字符串  
         */   
        public static String generateMixString(int length) {   
                StringBuffer sb = new StringBuffer();   
                Random random = new Random();   
                for (int i = 0; i < length; i++) {   
                        sb.append(allChar.charAt(random.nextInt(letterChar.length())));   
                }   
                return sb.toString();   
        }   
  
        /**  
         * 返回一个定长的随机纯大写字母字符串(只包含大小写字母)  
         *  
         * @param length 随机字符串长度  
         * @return 随机字符串  
         */   
        public static String generateLowerString(int length) {   
                return generateMixString(length).toLowerCase();   
        }   
  
        /**  
         * 返回一个定长的随机纯小写字母字符串(只包含大小写字母)  
         *  
         * @param length 随机字符串长度  
         * @return 随机字符串  
         */   
        public static String generateUpperString(int length) {   
                return generateMixString(length).toUpperCase();   
        }   
  
        /**  
         * 生成一个定长的纯0字符串  
         *  
         * @param length 字符串长度  
         * @return 纯0字符串  
         */   
        public static String generateZeroString(int length) {   
                StringBuffer sb = new StringBuffer();   
                for (int i = 0; i < length; i++) {   
                        sb.append('0');   
                }   
                return sb.toString();   
        }   
  
        /**  
         * 根据数字生成一个定长的字符串，长度不够前面补0  
         *  
         * @param num             数字  
         * @param fixdlenth 字符串长度  
         * @return 定长的字符串  
         */   
        public static String toFixdLengthString(long num, int fixdlenth) {   
                StringBuffer sb = new StringBuffer();   
                String strNum = String.valueOf(num);   
                if (fixdlenth - strNum.length() >= 0) {   
                        sb.append(generateZeroString(fixdlenth - strNum.length()));   
                } else {   
                        throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常！");   
                }   
                sb.append(strNum);   
                return sb.toString();   
        }   
  
        /**  
         * 根据数字生成一个定长的字符串，长度不够前面补0  
         *  
         * @param num             数字  
         * @param fixdlenth 字符串长度  
         * @return 定长的字符串  
         */   
        public static String toFixdLengthString(int num, int fixdlenth) {   
                StringBuffer sb = new StringBuffer();   
                String strNum = String.valueOf(num);   
                if (fixdlenth - strNum.length() >= 0) {   
                        sb.append(generateZeroString(fixdlenth - strNum.length()));   
                } else {   
                        throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常！");   
                }   
                sb.append(strNum);   
                return sb.toString();   
        }   
  
       /* public static void main(String[] args) {   
                System.out.println(generateString(15));   
                System.out.println(generateMixString(15));   
                System.out.println(generateLowerString(15));   
                System.out.println(generateUpperString(15));   
                System.out.println(generateZeroString(15));   
                System.out.println(toFixdLengthString(123, 15));   
                System.out.println(toFixdLengthString(123L, 15));   
        }   */
}  